In-line wheel chassis assembly

ABSTRACT

The invention provides an in-line wheel chassis assembly having three or more wheels mounted in an in-line (tandem) arrangement for rotation in a common vertical plane, such that the chassis assembly is configured to (i) facilitate independent vertical movement of at least two of the three or more wheels mounted on the chassis and (ii) distribute across the mounted wheels, total impact and displacement occurring responsive to encountering an obstacle, thereby staggering transmission of the impact and displacement to any surface to which the chassis is mounted. The invention additionally provides a method for manufacturing the in-line wheel chassis assembly, and an in-line skate comprising the in-line wheel chassis assembly.

FIELD OF THE INVENTION

The present invention relates to a chassis for an in-line assembly of wheels, such as a chassis for an in-line roller skate. The invention particularly provides a chassis for an in-line assembly of wheels, having an improved suspension system offering safety, impact distribution, shock absorption and improved performance on irregular or uneven surfaces.

BACKGROUND

Conventional in-line assemblies of wheels (such as in-line roller skates) perform optimally on smooth surfaces. Often however, such assemblies are subjected to rough and uneven surfaces, including cobbles, sidewalks, bike paths, streets and parks.

Prior art designs for in-line wheel assemblies are essentially rigid, and fully transmit shocks encountered at each wheel, through the chassis and onward to any load bearing surface supported by the chassis. In the case of in-line roller skates, shocks encountered at each wheel are transmitted to the skater's foot. This causes use of suspension-less in-line wheel assemblies on less-than-optimal surfaces, to be uncomfortable, fatiguing, and unsafe. While attempts have been made to reduce vibrations caused by rough roads, such as by adding spring suspensions to each wheel—these prior art solutions have been found to significantly increase complexity of construction and maintenance of the in-line wheel assemblies.

There is accordingly a need for developing a simple and sturdy chassis for in-line wheel assemblies, which is configured to provide independent suspension for each wheel, impact distribution and absorption, and maneuverability over uneven surfaces.

SUMMARY

The objective of the invention is to provide a chassis for an in-line wheel assembly having three or more wheels mounted in an in-line (tandem) arrangement for rotation in a common vertical plane, such that the chassis is configured to (i) facilitate independent vertical movement of at least two of the three or more wheels mounted on the chassis and (ii) distribute across the mounted wheels, total impact and displacement occurring responsive to encountering an obstacle, thereby staggering transmission of the impact and displacement to any surface to which the chassis is mounted.

It would be appreciated that this arrangement provides significant advantages, particularly where the chassis is mounted to a load bearing surface susceptible to impact—such as for example in the case of in-line skates, where impact at the wheels is transmitted through the chassis to a user's foot.

The invention provides an in-line wheel chassis assembly comprising n linearly arranged wheels and m rocker assemblies, such that m=(n−1). The n wheels are arranged in a front to rear linear configuration, comprising a front wheel, a rear wheel and at least one intermediate wheel located between the front wheel and the rear wheel. The m rocker assemblies include at least a front rocker assembly and a rear rocker assembly, each including a front end, a rear end, and a pivot point located such that said front end and rear end are pivotable about an axis of rotation passing through said pivot point. The front rocker assembly may be configured such that the front wheel is rotatably mounted at the front end of said front rocker assembly, and a wheel positioned immediately rearward of the front wheel is rotatably mounted at the rear end of said front rocker assembly. The rear rocker assembly may be configured such that the rear wheel is rotatably mounted at the rear end of the rear rocker assembly, the front end of the rear rocker assembly is coupled with a pivot point of a rocker assembly that rotatably mounts a wheel positioned immediately forward of the rear wheel, and the pivot point of the rear rocker assembly is pivotably coupled with a load bearing plate.

In an embodiment of the in-line wheel chassis assembly the m rocker assemblies may include at least one intermediate rocker assembly. The intermediate rocker assembly may comprise a front end, a rear end, and a pivot point located such that said front end and rear end are pivotable about said pivot point. An intermediate wheel may be located between the front wheel and the rear wheel, and may be rotatably mounted at the rear end of the intermediate rocker assembly. The front end of the intermediate rocker assembly may be coupled with a pivot point of a rocker assembly that rotatably mounts a wheel positioned immediately forward of the intermediate wheel.

In an embodiment, the axes of rotation corresponding to each of the n linearly arranged wheels, and the axes of rotation passing through pivot points on each rocker assembly are substantially parallel to each other. In another embodiment, the pivotable coupling between the pivot point of the rear rocker assembly and the load bearing plate is the only disengageable interconnection between the m interconnected rocker assemblies and the load bearing plate.

The front rocker assembly may in an embodiment, comprise an angled rocker arm connecting the front end and rear end of the front rocker assembly. The pivot point of said front rocker assembly may be located substantially at a vertex of the angled rocker arm. Further, the vertex of the angled rocker arm may be located further away from the load bearing plate than either of the front and rear ends of the front rocker assembly. In an embodiment of the in-line wheel chassis assembly radius of the front wheel may be greater than radius of the wheel positioned immediately rearward of said front wheel.

The invention additionally may provide an in-line skate comprising a skate boot and an in-line wheel chassis assembly in accordance with any of the embodiments described herein. In such embodiments, the load bearing plate of the in-line wheel chassis assembly comprises a foot plate, which foot plate may be affixed to the skate boot.

In an embodiment of the in-line skate, a toe portion of the skate boot or of the foot plate may be configured to conform to a surface of the front wheel, such that inclining the toe portion towards the front wheel causes said toe portion to interfere with motion of said front wheel thereby reducing motion of the inline skate. In another embodiment, at least one of the m rocker assemblies may include a support surface for supporting the foot plate. The inline skate may additionally comprise a resilient support affixed to the support surface for resiliently engaging with the foot plate. The support surface may include a longitudinal opening, wherein the resilient support may be affixed at a predetermined point within the longitudinal opening, which predetermined point is selected for optimizing support to the skate boot. In an embodiment, the resilient support may be is affixed to the longitudinal opening by an adjustable retainer, wherein said adjustable retainer enables repositioning of the resilient support at any point within the longitudinal opening.

The invention further provides a method for manufacturing the in-line wheel chassis assembly described above. The method comprises a first step of determining dimensions for each of the m rocker assemblies and locations for the front end, rear end and pivot point corresponding to each rocker assembly such that, for each of the n wheels, a ratio between displacement encountered at such wheel (Denc) and displacement intended for transmission to the load bearing plate (Dtrans) satisfies the following expression (I):

$\begin{matrix} {D_{trans} = {D_{enc}*\frac{\Pi_{k = 1}^{i}l_{k}}{\Pi_{k = 1}^{i}L_{k}}}} & {{Expression}\mspace{14mu} (I)} \end{matrix}$

and a second step of configuring and interconnecting each of the m rocker assemblies and the load bearing plate in accordance with the determined dimensions. For the purposes of Expression (I) (i) i represents the number of interconnected rocker assemblies used to connect a wheel at which displacement Denc is encountered, with the load bearing surface (ii) lk represents a horizontal distance between (a) a pivot point disposed on the kth rocker assembly and (b) a wheel axis or pivot point axis disposed on the kth rocker assembly at an end opposite to the end at which the displacement has been transmitted to said kth rocker assembly, and (iii) Lk represents a horizontal distance between an effective first end and an effective second end of the kth rocker assembly, wherein effective first and second ends:

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

FIGS. 1A to 1C illustrate rockers for rocker assemblies.

FIG. 2A illustrates an exemplary embodiment of a rocker assembly.

FIG. 2B illustrates arrangements to affix a wheel to a rocker arm.

FIGS. 3 and 4 illustrate a plurality of interconnected rocker assemblies for linearly mounting wheels in a front to rear configuration.

FIGS. 5A and 5B provide exemplary illustrations of a method for determining displacement transmitted by each wheel of a chassis assembly to a load bearing plate.

FIG. 6 illustrates an embodiment of an in-line wheel chassis assembly according to the present invention.

FIGS. 7A and 8 illustrate embodiments of in-line skates comprising the in-line wheel chassis assembly according to the present invention.

FIGS. 7B and 7C illustrate exemplary embodiments of parts of footplates for an in-line skate in accordance with the present invention.

FIGS. 9 and 10 illustrate exemplary embodiments of rockers in accordance with the present invention.

FIGS. 11 and 12 respectively show a resilient support for a foot plate, and implementation of said resilient support in the in-line wheel chassis assembly.

DETAILED DESCRIPTION

The present invention comprises a novel chassis assembly for an in-line wheel assembly having three or more wheels mounted in an in-line arrangement for rotation in a common vertical plane. The chassis is configured to (i) mount to a load bearing surface, (ii) facilitate independent vertical movement of at least two of the three or more wheels mounted on the chassis and (iii) distribute across the mounted wheels, total impact and displacement occurring responsive to encountering an obstacle, thereby staggering transmission of the impact and displacement to any surface to which the chassis is mounted.

While the chassis assembly within the present disclosure is discussed in terms of a chassis mounted to an in-line roller skate, it would be understood that this is entirely without prejudice to the generality of the invention, and potential applications thereof. Only by way of illustrative example, the novel configuration may be applied to a chassis mounted to any vehicle having an in-line arrangement of wheels, including without limitation, pallets for transporting goods, automobiles, wheel chairs, remotely guided toys and vehicles, robots, wheeled stretchers and gurneys.

The chassis assembly of the present invention may be applied to any in-line arrangement of at least three wheels, and is configured to facilitate independent vertical displacement of at least two of the three or more wheels relative to each other. The vertical displacement may occur in response to encountering some obstacle in or upon a surface being traversed by the wheel arrangement, and is achieved by constructing a chassis comprising an interconnected arrangement of rockers or rocker assemblies, such that each wheel is rotatably mounted on a wheel axle connected to a rocker or rocker assembly, which wheel may rotate about an axis formed by the wheel axle. Each rocker or rocker assembly is itself configured to rotate (or pivot) about a pivoting axis (e.g. a hinge pin or a pivot pin) located between two ends of said rocker or rocker assembly, which accordingly enables vertical displacement of each end of said rocker or rocker assembly by virtue of such pivoting action. In an embodiment of the invention, the pivoting axis is parallel or substantially parallel to one or more of the wheel axles within the chassis. The pivot and pivoting axis are located at a pivot point provided on the rocker or rocker assembly.

Materials for practicing the invention may include metals, plastics, polymers, ceramics, and composite materials. Metals may include steel, aluminum, magnesium, and alloys of such metals. Composite materials may include those brought about by combining materials differing in composition or form on a macro scale for the purpose of obtaining specific characteristics and properties. The constituents retain their identity such that they can be physically identified and they exhibit an interface between one another. Composite materials may include fibers such as carbon fibers in a synthetic matrix, such as a resin. Individual chassis components, such as arm components, axles, frames, rocker assemblies, etc., can be manufactured from single pieces of material or be made by joining two or more parts. In a preferred embodiment, where the chassis is a skate frame, a skate boot is made of a hard, resilient plastic and the skate frame and/or suspension system components are metal, preferably steel (or an alloy thereof) or aluminum. Auxiliary systems, e.g., brakes, “grind” plates, etc., may also be manufactured from these or other suitable materials.

The chassis assembly of the present invention comprises a suspension based on a plurality of rockers or rocker assemblies. For the purposes of the invention, a “rocker” refers to a component comprising one or more parts, said component having a first end and a second end and configured to support a wheel axle (and a corresponding wheel) at either the first end or the second end or both. In addition, the rocker is also configured to support a hinge or pivot that is parallel or substantially parallel to one or more wheel axles supported by the rocker. The pivot or hinge of the rocker enables the component to rotate about the axis of said pivot or hinge, thereby enabling vertical displacement of the first and second ends of the rocker. In a configuration where at least one wheel is attached to the rocker, the assembly of rocker and wheel shall for the purposes of the present description be referred to as a “rocker assembly”.

rocker according to the present invention comprises at least one rocker arm, to which at least one and upto two wheels may be attached. A rocker arm may take a variety of shapes, including crescent shaped, linear, angled, elbow shaped, curved upward or downward at one or both ends. Each rocker arm may comprise a first end and a second end. The first end may include a first end opening or hole, while the second end may include a second end opening or hole. Either or both of said first and second ends may be configured to support a wheel axle—typically by using the first and second end openings or holes to support either a wheel axle or bolts or other retainers for supporting a wheel axle. A pivot point comprising an additional opening or hole may be provided on the rocker arm, between the first and second ends, and configured to support a pivot pin or hinge pin such that the rocker arm may be rotatably disposed about an axis of the pivot pin or hinge pin. In a specific embodiment, the pivot point comprising an opening for supporting a pivot pin or hinge pin may be located off (i.e. away from) an axis joining the openings corresponding to said first end and second end. In another embodiment, the pivot point comprising an opening for supporting a pivot pin or hinge pin may be located on an axis joining the openings corresponding to said first end and second end.

FIGS. 1A to 1C illustrate exemplary embodiments of components 100 a, 100 b and 100 c that may be used as rockers for the purpose of supporting wheel axles. Each component respectively has a first end 101 a, 101 b and 101 c, and a second end 102 a, 102 b and 102 c. Each first end respectively includes hole 103 a, 103 b and 103 c while each second end respectively include hole 105 a, 105 b and 105 c. The hole at said first ends or second ends may be used to support a wheel axle. Additionally, rockers 100 a, 100 b and 100 c respectively include hole 104 a, 104 b and 104 c, positioned between, the first and second ends of each rocker, which hole may support a pivot pin or hinge pin. It would be understood that when a rocker is rotatably suspended about a pivot pin supported by hole 104 a, 104 b or 104 c, the first end and second end of said rocker would pivot about the axis of said pivot pin. In the event, the axis of a pivot pin coincides with or is substantially coincident with a horizontal plane, pivoting action of said first and second ends of the rocker would necessarily result in displacement of said first and second ends within a vertical plane, and consequent vertical displacement of any wheel attached at either said first end or said second end. It would also be understood that as a consequence of the pivoting arrangement, displacement of the first end of the rocker arm in a first vertical direction, results in a corresponding displacement of the second end of the rocker arm in a second vertical direction opposite to the first vertical direction.

A wheel may be affixed to a rocker arm using a wheel axle assembly. In an example, a bolt may comprise the axle and may extend through an opening in the rocker arm. The axle assembly may include a retainer to keep the wheel from coming of the axle after attachment to the rocker arm. Alternatively, the rocker arm may have an integrated axle for a wheel, with the wheel being retained by a nut, bolt, or both, at the axle end opposite the end attached to the rocker arm.

In an embodiment of the invention, a rocker may comprise a pair of kicker arms between which one or more wheels can be mounted. Both rocker arms within a rocker arm pair may have an identical shape. Alternatively, a first rocker arm within a rocker arm pair may be a mirror image of the second rocker arm. FIG. 2A illustrates an exemplary embodiment of a rocker assembly 200, comprising a rocker having a pair of rocker arms 201 and 202, between which a pair of wheels 203 and 204 have been affixed, such that said wheels respectively rotate about wheel axles 205 and 206. Wheels 203 and 204 may respectively be mounted at wheel axles 205 and 206 located at first and second ends of the rocker arm pair.

FIG. 2B illustrates an exemplary arrangement for an axle assembly 207 designed to affix a wheel to a rocker arm or between a rocker arm pair. In the illustrated embodiment, axle assembly 207 comprises axle 208 having a bolt portion 209 and a head portion 210. Bolt portion 209 is sized to pass through an opening in a rocker arm, while head portion 210 is sized to resist passage through said rocker arm opening. Bolt portion 209 accordingly is passed through the opening in the rocker arm until head portion 210 engages with the rocker arm and prevents further passage of the bolt portion. A wheel may thereafter be mounted upon the shaft of bolt portion 209, and retainer 211 may be affixed to an end of bolt portion 209 which is disposed opposite to head portion 210. In the illustrated embodiment retainer 211 comprises head portion 212 and shank portion 213, and is affixed to axle 208 by extending shank portion 213 into an opening in bolt portion 209, which opening is sized to accommodate shank portion 213. In an embodiment, the opening in bolt portion 209 and shank portion 213 may each be provided with complementary threads to provide mating engagement therebetween. Upon engagement of retainer 211 with axle 208, head portion 212 of retainer 211 prevents a wheel mounted upon axle 208 from being inadvertently dismounted. It would be understood that the axle assembly 207 or any other similar arrangement may be applied to rockers and rocker assemblies comprising either single arms or rocker arm pairs.

The chassis assembly of the present invention comprises a load bearing plate and a frame affixed thereto. The load bearing plate comprises a plate for engaging with or being affixed to a load bearing surface, which supports the load bearing surface and which prevents said load bearing surface from engaging with wheels of the chassis assembly. In an embodiment of the invention where the chassis assembly comprises a frame for an in-line skate, the load bearing plate comprises a footplate which engages with a boot or shoe of the in-line skate.

The chassis assembly includes a frame comprising a plurality of interconnected rocker assemblies, which linearly mount n wheels in a front to rear linear configuration, where n≧3 wheels, and all n wheels are configured to rotate in a common vertical plane. For the purposes of this disclosure, the leading wheel in the linear configuration of wheels shall be referred to as the front wheel, the trailing wheel in the linear configuration of wheels shall be referred to as the rear wheel, and each wheel disposed between the front wheel and the rear wheel shall be referred to as an intermediate wheel.

The chassis assembly comprises m interconnected rocker assemblies for linearly mounting the n wheels, such that:

m=(n−1)

Of the m interconnected rocker assemblies within the chassis assembly of the present invention, a first rocker assembly comprises a front end, a rear end, and a pivot point positioned between the front end and rear end of said first rocker. The front wheel of the chassis assembly is rotatably mounted at the front end of the first rocker. A wheel positioned immediately behind the front wheel, in the front to rear linear arrangement of wheels, is rotatably mounted at the rear end of the first rocker.

The m^(th) rocker assembly within the chassis assembly comprises a front end, a rear end, and a pivot point positioned between the front end and rear end of said m^(th) rocker assembly. The rear wheel of the chassis assembly is rotatably mounted at the rear end of the m^(th) rocker assembly. The front end of the m^(th) rocker assembly is coupled with a rocker assembly that rotatably mounts a wheel which is positioned immediately ahead of the rear wheel—which coupling is implemented at a pivot point of said other rocker assembly. The pivot point of the m^(th) rocker assembly is coupled with the load bearing plate using a hinge or pivot—as a consequence of which, the m^(th) rocker assembly is configured to rotate or pivot about a pivoting axis of said hinge or pivot, thereby enabling vertical displacement of the rear wheel relative to the pivot and the load bearing plate.

Additionally, each rocker assembly intermediately positioned between the first rocker assembly and the m^(th) rocker assembly, within the arrangement of m interconnected rocker assemblies, comprises a front end, a rear end, and a pivot point positioned between the front end and rear end of said intermediately positioned rocker assembly. An intermediate wheel of the chassis assembly is rotatably mounted at the rear end of the intermediately positioned rocker assembly. The front end of the intermediately positioned rocker assembly is coupled with another rocker assembly that rotatably mounts a wheel which is positioned immediately ahead of the intermediate wheel. In an embodiment, the front end of the intermediately, positioned rocker assembly is coupled with such other rocker assembly at the pivot point of said other rocker assembly, using a hinge or pivot—as a consequence of which said other rocker assembly is capable of rotating or pivoting about a pivoting axis of said hinge or pivot, thereby enabling vertical displacement of the first end and second end of said other rocker assembly (and any wheel(s) mounted thereon) relative to the pivot and the load bearing plate. As a consequence of the pivot arrangement, displacement of the first end of said other rocker assembly in a first vertical direction would result in a corresponding displacement of the second end of said other rocker assembly in a second vertical direction opposite to the first vertical direction.

It will be understood that for the purposes of the invention, rotatable mounting of wheels within rocker assemblies, and interconnection of rocker assemblies within the chassis assembly is configured to ensure that wheels within the chassis assembly all rotate in a common vertical plane.

The arrangement of interconnected rocker assemblies within the chassis assembly may be understood more fully with reference to FIGS. 3 and 4.

FIG. 3, illustrates an embodiment of the invention wherein a plurality of interconnected rocker assemblies is used for linearly mounting n wheels in a front to rear linear configuration, such that n=3 wheels. As would be observed from FIG. 3, each of the three wheels 301, 302 and 303 are mounted to rotate within a single vertical plane. Assuming that the illustrated left to right configuration of wheels shown in FIG. 3 corresponds to a front to rear configuration, wheel 301 is the front wheel, wheel 302 is an intermediate wheel, and wheel 303 is a rear wheel. Each of wheels 301, 302 and 303 are respectively mounted for rotation about one of axles, 304, 305 and 306.

As discussed in the more general case above, the chassis assembly comprises m interconnected rocker assemblies for linearly mounting the n wheels, such that m=(n−1) rocker assemblies. Since n=3, the value of m is therefore (3−1) i.e. two interconnected rocker assemblies 307 and 308. Each rocker assembly illustrated in FIG. 3 comprises a pair of rocker arms configured in the manner discussed above.

Of the two interconnected rocker assemblies, first rocker assembly 307 comprises front end 309, 309 a, rear end 310, 310 a, and pivot point 311, 311 a positioned between said front end and rear end of said first rocker assembly 307. The front wheel 301 of the chassis assembly is rotatably mounted at front end 309, 309 a. Wheel 302 positioned immediately behind front wheel 301 in the front to rear linear arrangement of wheels, is rotatably mounted at the rear end 310, 310 a.

In FIG. 3, m=2, and the second rocker assembly 308 is accordingly also the m^(th) rocker, assembly within the chassis assembly. The second rocker assembly 308 comprises front end 312, 312 a, rear end 313, 313 a, and pivot point 314, 314 a positioned between the front end and rear end of said second rocker assembly 308. The rear wheel 303 of the chassis assembly is rotatably mounted at rear end 313, 313 a of the second rocker assembly 308.

The front end 312, 312 a of second rocker assembly 308 is coupled with a rocker assembly which rotatably mounts a wheel positioned immediately ahead of rear wheel 303. In other words, front end 312, 312 a of second rocker assembly 308 is coupled with first rocker assembly 307—which coupling is implemented at pivot point 311, 311 a of first rocker assembly 307 by means of a pivot or hinge. While not illustrated in FIG. 3, pivot point 314, 314 a of second rocker assembly 308 may be coupled with a load bearing plate using a hinge or pivot as a consequence of which, second rocker assembly 308 is pivotable about a pivoting axis of said hinge or pivot, thereby enabling vertical displacement of the rear wheel relative to the pivot and the load bearing plate.

Since the embodiment of FIG. 3 only comprises two rocker assemblies, there are no intermediate rocker assemblies positioned between first rocker assembly 307 and second rocker assembly 308.

FIG. 4, illustrates another exemplary embodiment of the invention wherein a plurality of interconnected rocker assemblies is used for linearly mounting n wheels in a front to rear linear configuration, such that n=4 wheels. As would be observed from FIG. 4, each of the four wheels 401, 402, 403 and 404 are mounted to rotate within a single vertical plane. Assuming that the illustrated left to right configuration of wheels shown in FIG. 4 corresponds to a front to rear configuration, wheel 401 is the front wheel, wheels 402 and 403 are intermediate wheels, and wheel 404 is the rear wheel. Each of wheels 401, 402, 403 and 404 are respectively mounted for rotation about an axle.

As discussed earlier, the illustrated chassis assembly comprises m interconnected rocker assemblies for linearly mounting the n wheels, such that m=(n−1) rocker assemblies. Since n=4, the value of m is therefore (4−1) i.e. three interconnected rocker assemblies 407, 408 and 409. While each rocker assembly illustrated in FIG. 4 comprises a pair of rocker arms configured in the manner discussed above, for convenience in describing FIG. 4, reference numerals have only been provided in connection with one of the pair of rocker arms.

Of the three interconnected rocker assemblies, first rocker assembly 407 comprises a front end 410, a rear end 411, and a pivot point 412 positioned between the front end and rear end of said first rocker assembly 407. The front wheel 401 of the chassis assembly is rotatably mounted at the front end 410 of the first rocker assembly 407. Wheel 402 positioned immediately behind front wheel 401 is rotatably mounted at the rear end 411 of the first rocker assembly 407.

In FIG. 4, since m=3, the third rocker assembly 409 is the m^(th) rocker assembly within the chassis assembly. Third rocker assembly 409 comprises a front end 413, a rear end 414 and a pivot point 415 positioned between the front end and rear end of said third rocker assembly 409. The rear wheel 404 of the chassis assembly is rotatably mounted at the rear end 414 of the third rocker assembly 409.

Front end 413 of third rocker assembly 409 is coupled with a rocker assembly which rotatably mounts a wheel positioned immediately ahead of rear wheel 404. In other words, front end 413 of third rocker assembly 409 is coupled with second rocker assembly 408 on which wheel 403 is rotatably, mounted—and which coupling is implemented at pivot point 417 of second rocker assembly 408 by means of a pivot or hinge. While not illustrated in FIG. 4, pivot point 415 of third rocker assembly 409 may be coupled with a load bearing plate using a hinge or pivot—as a consequence of which, third rocker assembly 409 is pivotable about a pivoting axis of said hinge or pivot, thereby enabling vertical displacement of the rear wheel 404 relative to the pivot and the load bearing plate.

Since the embodiment of FIG. 4 comprises only three rocker assemblies, second rocker assembly 408 comprises the only intermediately positioned rocker assembly between the first rocker assembly and the third rocker assembly. Second rocker assembly comprises a front end 422, a rear end 416, and a pivot point 417 positioned between the front end and rear end of said intermediately positioned rocker assembly 408. Intermediate wheel 403 of the chassis assembly is rotatably mounted at the rear end 416 of the second rocker assembly 408. The front end 422 of second rocker assembly 408 is coupled with another rocker assembly that rotatably mounts a wheel which is positioned immediately ahead of the intermediate wheel. In other words, front end 422 of second rocker assembly 408 is coupled with first rocker assembly 407 on which wheel 402 is rotatably mounted—and which coupling is implemented at pivot point 422 of first rocker assembly 407 by means of a pivot or hinge 420—as a consequence of which first rocker assembly 407 is capable of rotating or pivoting about a pivoting axis of said hinge or pivot 420, thereby enabling vertical displacement of the first end 410 and second end 411 of said first rocker assembly (and wheel(s) 401 and 402 mounted thereon) relative to the pivot 420 and the load bearing plate. As a consequence of the pivot arrangement, displacement of the first end 410 of said first rocker assembly 407 in a first vertical direction would result in a corresponding displacement of the second end 411 of said first rocker assembly 407 in a second vertical direction opposite to the first vertical direction.

In the embodiment illustrated in FIG. 4, it will be observed that third rocker assembly 409 additionally comprises support surface 421. Support surface 421 engages with and provides support for a load bearing surface coupled to the chassis assembly, and may additionally prevent said load bearing surface from interfering with movement of one or more wheels within the chassis assembly.

While the above embodiments cover three and four wheeled arrangements of the invention, it would be understood that the invention can be applied to any arrangement where the total number of wheels n is selected such that n≧3, by following the configuration described generally hereinabove.

It will be observed that the inventive configuration for a chassis assembly is achieved by means of a plurality of interconnected rocker assemblies, wherein a pivotable coupling lies between every pair of adjacent wheels in the chassis assembly. Referring to the exemplary embodiment in FIG. 3, pivot point 311, 311 a lies between adjacent wheels 301 and 302, while pivot point 314, 314 a lies between adjacent wheels 302 and 303. Referring to the embodiment illustrated in FIG. 4, pivot point 412 lies between adjacent wheels 401 and 402, pivot point 417 lies between adjacent wheels 402 and 403, and pivot point 415 lies between adjacent wheels 403 and 404. By providing a pivot point between each pair of adjacent wheels in the linear configuration of wheels housed in the chassis assembly, the invention ensures that each wheel within the chassis assembly is capable of vertical displacement relative to an adjacent wheel. Accordingly, responsive to encountering a surface obstacle (such as a surface protuberance or a surface depression), the wheel encountering such obstacle would undergo vertical displacement to conform to the contour of the surface obstacle, without affecting contact between the remaining wheels and the surface. Further, owing to forward motion of the chassis assembly, each wheel may displace vertically as it encounters the surface obstacle, allowing the chassis assembly to appropriately traverse rough or uneven terrain.

Additionally, since the chassis assembly may be coupled to a load bearing surface only at a single point (i.e. at the pivot point of the m^(th) rocker assembly), impacts encountered at each wheel of the chassis assembly necessarily require to traverse a series of interconnected rocker assemblies, starting from the rocker assembly at which the impact was encountered (i.e. at a rocker assembly which mounts a wheel at which the impact was encountered), upto the m^(th) rocker assembly—which interconnected rocker assemblies absorb some of the impact, and serve as a suspension which reduces the total impact transmitted to the load bearing surface.

Yet further, in view that each wheel is capable of vertical displacement in response to encountering a surface irregularity, without affecting surface contact of adjacent wheels, the corresponding displacement transmitted to the load bearing surface in response to a surface obstacle or irregularity encountered by the chassis assembly may be staggered across the n wheels housed within the chassis assembly. So for an obstacle of height h encountered by the chassis assembly, a corresponding displacement D_(enc) (where D_(enc)=h) may be transmitted to the load bearing surface in a staggered manner such that only a percentage (D_(trans)) of the total displacement is transmitted to the load bearing surface, as each wheel encounters the obstacle.

Specifically, for a chassis assembly comprising a linear configuration of n wheels in accordance with the present invention, it has been found that responsive to encountering an obstacle of height or depth equal to D_(enc), the average vertical displacement D_(av) transmitted to the load bearing surface as each wheel encounters said obstacle may be calculated by the formula:

$D_{av} = \frac{D_{enc}}{n}$

In designing a configuration for the chassis assembly of the present invention or manufacturing a chassis assembly according to the present invention, the skilled person may accordingly select a desired number of wheels for the chassis assembly, with a view to ensure that displacement transmitted to the load bearing surface, per wheel, does not exceed a predefined average displacement.

Additionally, it has been found that positioning of pivot points within rocker assemblies of the chassis assembly, determines displacement transmitted to the load bearing surface in response to vertical displacement of a specific wheel. Specifically, the relationship between (i) positioning of pivot points within rocker assemblies (ii) displacement encountered (D_(enc)) at a wheel, and (iii) displacement transmitted to the load bearing surface (D_(trans)) may be expressed as follows:

$\begin{matrix} {D_{trans} = {D_{enc}*\frac{\Pi_{k = 1}^{i}l_{k}}{\Pi_{k = 1}^{i}L_{k\;}}}} & {{Expression}\mspace{14mu} (I)} \end{matrix}$

wherein:

-   -   i is the number of interconnected rocker assemblies used to         connect a wheel at which displacement D_(enc) is encountered,         with the load bearing surface;     -   l_(k) is the horizontal distance between (i) a pivot point         disposed on the k^(th) rocker assembly and (ii) a wheel axis or         pivot point axis disposed on the k^(th) rocker assembly at an         end opposite to the end at which the displacement has been         transmitted to said k^(th) rocker assembly; and     -   L_(k) is the horizontal distance between an effective first end         and an effective second end of the k^(th) rocker assembly. It         would be understood that the effective first end and effective         second end comprise points on a rocker assembly at which         displacement may be transmitted to said rocker assembly. For a         rocker assembly connecting a front wheel and an adjacent wheel,         the effective first end and second end would comprise the points         at which said rocker assembly engages with wheel axes of said         front wheel and said adjacent wheel. For all other rocker         assemblies, an effective first end would comprise the point at         which said rocker assembly engages with a pivot point of another         rocker assembly, while said effective second end would comprise         the point at which the rocker assembly engages with a wheel         axis.

Based on the above relationship, a chassis assembly may be configured such that total displacement arising as a consequence of encountering an obstacle, may be transmitted to a load bearing surface in an optimally staggered fashion by specifically determining the displacement transmitted to the load bearing surface responsive to each wheel encountering the obstacle. By appropriate selection of lengths of rocker arms for each rocker assembly, and positioning pivot points at appropriate points on said rocker arms in accordance with the above Expression (I), a manufacturer can ensure that the chassis assembly conforms to specified requirements regarding wheel specific transmission of displacement to a load bearing surface.

As a general rule however, it would be understood that there is an inverse relationship between (i) path distance that an encountered displacement requires to be transmitted along interconnected rockers to reach the pivot point at which the chassis assembly is coupled with a load bearing plate, and (ii) displacement transmitted to the load bearing plate. An increase in path distance results in a corresponding decrease in transmitted displacement and vice versa. Additionally, in the event the path distance between the pivot coupling with the load bearing plate and each wheel is equal, each wheel would transmit an equal part of the total encountered displacement to the load bearing plate.

FIGS. 5A and 5B provide illustrative examples of an application of Expression (I) in determining displacement transmitted by each wheel of a chassis assembly to a load bearing plate.

FIG. 5A illustrates an embodiment of the invention wherein, the chassis assembly comprises a linear arrangement of three wheels, w₁, w₂ and w₃. Wheel w₁ is mounted on axle ax₁, wheel w₂ is mounted on axle ax₂, and wheel w₃ is mounted on axle ax₃. For the purposes of the illustration, the chassis assembly is understood to comprise two interconnected rockers, wherein a first rocker assembly is represented by the line ax₁-ax₂, having a first end at ax₁ and a second end at ax₂. Wheels w₁ and w₂ are understood to be mounted at each end of said line. Rocker assembly ax₁-ax₂ is understood to have a pivot point located at p₁.

A second rocker assembly is represented by the line joining, p₁ and ax₃, having a first end at p₁ and a second end at ax₃. A first end of the second rocker assembly is connected to pivot point p₁ of the first rocker assembly, and wheel w₃ is understood to be mounted at a second end of said second rocker assembly. The second rocker assembly is understood to have a pivot point located at p₂, at which the chassis assembly is connected to a load bearing surface.

Applying expression (I), displacement transmitted by each wheel to a load bearing surface connected at pivot point p₃ may be calculated in the following manner:

For wheel w₁:

$D_{trans} = {D_{{enc}\;}*\frac{\Pi_{k = 1}^{2}l_{k}}{\Pi_{k = 1}^{2}L_{k}}}$ ${{i.e}\mspace{14mu} D_{trans}} = {D_{enc}*\frac{l_{1}*l_{2}}{L_{1}*L_{2\;}}}$

wherein

-   -   D_(enc) is displacement encountered at wheel w₁     -   D_(trans) is displacement transmitted by wheel w₁ to a load         bearing surface connected to the chassis assembly at pivot point         p₂     -   l₁ is the horizontal distance between p₁ and ax₂     -   l₂ is the horizontal distance between p₂ and ax₃     -   L₁ is the horizontal distance between ax₁ and ax₂     -   L₂ is the horizontal distance between p₁ and ax₃         For wheel w₂:

$D_{trans} = {D_{{enc}\;}*\frac{\Pi_{k = 1}^{2}l_{k}}{\Pi_{k = 1}^{2}L_{k}}}$ ${i.e.\mspace{14mu} D_{trans}} = {D_{enc}*\frac{l_{1}*l_{2}}{L_{1}*L_{2\;}}}$

wherein

-   -   D_(enc) is displacement encountered at wheel w₂     -   D_(trans) is displacement transmitted by wheel w₂ to a load         bearing surface connected to the chassis assembly at pivot point         p₂     -   l₁ is the horizontal distance between p₁ and ax₁     -   l₂ is the horizontal distance between p₂ and ax₃     -   L₁ is the horizontal distance between ax₁ and ax₂     -   L₂ is the horizontal distance between p₁ and ax₃         For wheel w₃:

$D_{trans} = {D_{{enc}\;}*\frac{\Pi_{k = 1}^{1}l_{k}}{\Pi_{k = 1}^{1}L_{k}}}$ ${i.e.\mspace{14mu} D_{trans}} = {D_{enc}*\frac{l_{1}}{{L_{1}}_{\;}}}$

wherein

-   -   D_(enc) is displacement encountered at wheel w₃     -   D_(trans) is displacement transmitted by wheel w₃ to a load         bearing surface connected to the chassis assembly at pivot point         p₂     -   l₁ is the horizontal distance between p₁ and p₂     -   L₁ is the horizontal distance between p₁ and ax₃

FIG. 5B illustrates an embodiment of the invention wherein the chassis assembly comprises a linear arrangement of three wheels, w₁, w₂, w₃ and w₄. Wheel w₁ is mounted on axle ax₁, wheel w₂ is mounted on axle ax₂, wheel w₃ is mounted on axle ax₃ and wheel w₄ is mounted on axle ax₄. For the purposes of the illustration, the chassis assembly is understood to comprise three interconnected rockers, wherein a first rocker assembly is represented by the line ax₁-ax₂, having a first end at ax₁ and a second end at ax₂. Wheels w₁ and w₂ are understood to be mounted at each end of said line. Rocker assembly ax₁-ax₂ is understood to have a pivot point located at p₁.

A second rocker assembly is represented by the line joining p₁ and ax₃, having a first end at p₁ and a second end at ax₃. A first end of the second rocker assembly is connected to pivot point p₁ of the first rocker assembly, and wheel w₃ is understood to be mounted at a second end of said second rocker assembly. The second rocker assembly is understood to have a pivot point located at p₂.

A third rocker assembly is represented by the line joining p₂ and ax₄, having a first end at p₂ and a second end at ax₄. A first end of the third rocker assembly is connected to pivot point p₂ of the second rocker assembly, and wheel w₄ is mounted at a second end of said third rocker assembly. The third rocker assembly is understood to have a pivot point located at p₃, at which the chassis assembly is connected to a load bearing surface.

Applying expression (I), displacement transmitted by each wheel to a load bearing surface connected at pivot point p₃ may be calculated in the following manner:

For wheel w₁:

$D_{trans} = {D_{{enc}\;}*\frac{\Pi_{k = 1}^{3}l_{k}}{\Pi_{k = 1}^{3}L_{k}}}$ ${i.e.\mspace{14mu} D_{trans}} = {D_{enc}*\frac{l_{1}*l_{2}*l_{3}}{L_{1}*L_{2}*L_{3}}}$

wherein

-   -   D_(enc) is displacement encountered at wheel w₁     -   D_(trans) is displacement transmitted by wheel w₁ to a load         bearing surface connected to the chassis assembly at pivot point         p₃     -   l₁ is the horizontal distance between p₁ and ax₂     -   l₂ is the horizontal distance between p₂ and ax₃     -   l₃ is the horizontal distance between p₃ and ax₄     -   L₁ is the horizontal distance between ax₁ and ax₂     -   L₂ is the horizontal distance between p₁ and ax₃     -   L₃ is the horizontal distance between p₂ and ax₄         For wheel w₂:

$D_{trans} = {D_{{enc}\;}*\frac{\Pi_{k = 1}^{3}l_{k}}{\Pi_{k = 1}^{3}L_{k}}}$ ${i.e.\mspace{14mu} D_{trans}} = {D_{enc}*\frac{l_{1}*l_{2}*l_{3}}{L_{1}*L_{2}*L_{3}}}$

wherein

-   -   D_(enc) is displacement encountered at wheel w₂     -   D_(trans) is displacement transmitted by wheel w₂ to a load         bearing surface connected to the chassis assembly at pivot point         p₃     -   l₁ is the horizontal distance between p₁ and ax₁     -   l₂ is the horizontal distance between p₂ and ax₃     -   l₃ is the horizontal distance between p₃ and ax₄     -   L₁ is the horizontal distance between ax₁ and ax₂     -   L₂ is the horizontal distance between p₁ and ax₃     -   L₃ is the horizontal distance between p₂ and ax₄         For wheel w₃:

$D_{trans} = {D_{{enc}\;}*\frac{\Pi_{k = 1}^{2}l_{k}}{\Pi_{k = 1}^{2}L_{k}}}$ ${i.e.\mspace{14mu} D_{trans}} = {D_{enc}*\frac{l_{1}*l_{2}}{L_{1}*L_{2\;}}}$

wherein

-   -   D_(enc) is displacement encountered at wheel w₃     -   D_(trans) is displacement transmitted by wheel w₃ to a load         bearing surface connected to the chassis assembly at pivot point         p₃     -   l₁ is the horizontal distance between p₁ and p₂     -   l₂ is the horizontal distance between p₃ and ax₄     -   L₁ is the horizontal distance between p₁ and ax₃     -   L₂ is the horizontal distance between p₂ and ax₄         For wheel w₄:

$D_{trans} = {D_{{enc}\;}*\frac{\Pi_{k = 1}^{1}l_{k}}{\Pi_{k = 1}^{1}L_{k}}}$ ${i.e.\mspace{14mu} D_{trans}} = {D_{enc}*\frac{l_{1}}{{L_{1}}_{\;}}}$

wherein

-   -   D_(enc) is displacement encountered at wheel w₄     -   D_(trans) is displacement transmitted by wheel w₄ to a load         bearing surface connected to the chassis assembly at pivot point         p₃     -   l₁ is the horizontal distance between p₂ and p₃     -   L₁ is the horizontal distance between p₂ and ax₄

As discussed above, rocker assemblies (and rocker arms disposed therein) may take a variety of shapes, including crescent shaped, linear, angled, elbow shaped, curved upward or downward at one or both ends. The shape and length of rocker arms and rocker assemblies may be selected based on a variety of factors including anticipated terrain, size of wheels of the chassis assembly, percentage of encountered displacement that is sought to be transmitted by each wheel to the load bearing surface.

In an embodiment of the invention, the rocker assembly which mounts the front wheel and also the wheel positioned adjacent to and immediately behind the front wheel (i.e. the second wheel) comprises a rocker arm having an angled or elbow shape (such as for example, illustrated in FIG. 1A). Additionally, said angled rocker arm may be used to mount the front wheel and the second wheel such when the front wheel and second wheel both rest on the same horizontal plane, the vertex of said angled rocker arm is positioned closer to said horizontal plane than the ends thereof.

FIG. 6 illustrates an embodiment of a five wheeled chassis assembly, wherein the front wheel w₁ and second wheel w₂ are mounted respectively at wheel axes ax₁ and ax₂ on angled rocker arm R₁. On encountering obstacle Obst having height h, wheel w₁ would undergo vertical displacement corresponding to height h, without affecting the position of wheel w₂. As wheel w₁ encounters obstacle Obst, force F acts upon wheel w₁ in a direction opposed to motion of the chassis assembly. Said force acting upon wheel w₁ at wheel axis ax₁ causes rocker arm R₁ (and consequently wheel w₁) to pivot upward at pivot point p₁.

It is understood that torque (τ) is the product of magnitude of force (F) and a perpendicular distance (P_(d)) between from the point of incidence of the force and the axis of rotation, i.e.:

τ=F×P _(d)

Accordingly, for a given force encountered, torque at wheel w₁ would increase as the perpendicular distance between wheel axle ax₁ and pivot point p₁ increases. Magnitude of angle of the rocker arm mounting wheel w₁ and distance between wheel axle ax₁ and pivot point p₁ may each be selected so as to specifically determine the force required to vertically displace the front wheel in response to an encountered obstacle. It would be understood that the greater the magnitude of torque that is generated in response to encountering of an obstacle, the more easily the front wheel would be vertically displaced to enable traversal of the encountered obstacle. Correspondingly, as the angle of the rocker arm becomes more acute, and/or the distance between wheel axle ax₁ and pivot point p₁ becomes larger, torque delivered at the wheel increases.

In an embodiment of the invention, the front wheel may have a larger wheel radius than the second wheel, specifically to ensure a larger perpendicular distance between wheel axle ax₁ and pivot point p₁, and consequent increase in torque.

The above arrangements including one or more of (i) provision of a vertically displaceable front wheel, (ii) provision of an angled rocker arm for mounting the front wheel and (iii) providing a front wheel having a larger radius than the immediately adjacent wheel, which allows the front wheel of the chassis assembly to traverse obstacles that may have a height greater than the radius of such front wheel. This is an advantage over wheel arrangements which do not have vertically displaceable front wheels, as such prior art arrangements are unable to traverse obstacles having a height greater than the wheel radius. Once the front wheel of the chassis assembly traverses the obstacle, the remaining wheels would follow over such obstacle.

It would be understood that the chassis assembly of the present invention has a plurality of applications, as discussed above. In a preferred embodiment however, the chassis assembly is a chassis assembly of an in-line skate. It would be understood that when implemented in an in-line skate, the load bearing plate of the inventive chassis assembly is a foot plate configured to accommodate and engage with a skate boot mounted thereon.

FIG. 7A illustrates an embodiment of an in-line skate comprising the chassis assembly described above. In the illustrated embodiment, the chassis assembly comprises a total of five wheels w₁, w₂, w₃, w₄ and w₅, and four interconnected rocker assemblies R₁, R₂, R₃ and R₄, which rocker assemblies mount said wheels. In the illustrated embodiment, rocker assembly R₄ mounts rear wheel w₅, and is additionally pivotably coupled with a foot plate f_(plate) at its pivot point p₅. Foot plate f_(plate) in turn supports skate boot B.

FIGS. 7B and 7C respectively illustrate a side view of a rear part of footplate and a top view of a front part of footplate f_(plate), which footplate functions as a load bearing plate in an implementation of the chassis assembly in an in-line skate. It will be observed that the footplate f_(plate) is provided with a pivot point f_(pivot) at which said footplate may be pivotably engaged with a rocker assembly of the chassis assembly.

While the embodiment of the in-line skate illustrated in FIG. 7A relates to a chassis assembly comprising five wheels, this number can modified, and in a preferred embodiment may include between 3 and 20 wheels.

FIG. 8 illustrates another embodiment of the invention wherein the chassis assembly comprises a total of four wheels w₁, w₂, w₃, and w₄.

Since pivotable engagement between foot plate f_(plate) and the chassis assembly is achieved by a single pivot, foot plate f_(plate) is capable of vertical displacement, without causing the wheels to disengage from a skating surface. In the embodiment illustrated in FIG. 8, it would be observed that the foot plate and boot are both at an incline to the horizontal skating surface, while all four wheels remain in contact with the surface. This offers multiple advantages, including that a skater may incline a skate boot mounted on foot plate f_(plate) either forward or rearward to engage a forwardly disposed toe brake, or a rearwardly disposed heel brake, without causing skate wheels to disengage from the skating surface. This has been found to be particularly advantageous when the skater is traversing an inclined skating surface. In a particular embodiment of the invention, the toe portion of the skate boot, or of the foot plate may be configured to engage with or conform to the shape of a front wheel such that by inclining the toe portion forward, engagement between said toe portion and front wheel causes a braking effect. This has been found to be particularly effective when traversing an inclined surface in an upslope direction, or when the front wheel of the in-line skate has been vertically displaced in an upward direction upon encountering an obstacle—for the reason that use of the toe portion for braking serves to keep the skater's centre of gravity forward.

In the embodiment illustrated in FIG. 8, it would additionally be observed that size of front wheel w₁ is greater than the size of wheel w₂ that is positioned immediately adjacent to wheel w1. Based on the description above, it would be understood that the size difference in wheel size of the front and second wheels increases the moment of force (torque) encountered at the front wheel, with consequent improvements in maneuverability of the wheels over encountered obstacles.

FIGS. 9 and 10 respectively illustrate specific embodiments of rocker arms that are particularly advantageous for use when the chassis assembly is implemented within an in-line skate.

FIG. 9 illustrates a rocker arm 900 having openings 901 and 901′ at a first end, openings 902 and 902′ at a second end, and openings 903 and 903′ at a pivot point. As discussed earlier, openings at the first end and the second end may be used to mount a wheel, or to engage with an adjacent rocker assembly at a pivot point of said adjacent rocker assembly. Openings at the pivot point may be used to accommodate a pivot pin or hinge pin Additionally, rocker arm 900 is provided with support surface 904, which supports a load bearing surface or a foot plate, and which prevents the supported portion of the load bearing surface or footplate from interfering with one or more wheels mounted within the chassis assembly.

FIG. 10 illustrates a rocker arm 1000 having openings 1001 and 1001′ at a first end, openings 1002 and 1002′ (not shown) at a second end, and openings 1003 and 1003′ which serve as a pivot point and which accommodate a pivot pin or hinge pin. Openings at the first end and the second end may be used to mount a wheel, or to connect or engage with an adjacent rocker assembly at a pivot point of said adjacent rocker assembly. Additionally, rocker arm 1000 is provided with support surface 1004, which provides support for a load bearing surface or a foot plate, and prevents the supported portion of the load bearing surface or footplate from interfering with wheels mounted within the chassis assembly.

In an exemplary embodiment of the invention rocker arm 1000 illustrated in FIG. 10 is implemented within the chassis assembly to mount the rear wheel, and engage with a footplate of an in-line skate at pivot points 1003 and 1003′. When used to mount the rear wheel of a chassis assembly, arms 1006, 1006′ and 1006″ act as strengthening struts for the rocker assembly and also provide a mount for a heel operated rear brake pad. Reference to FIGS. 6 and 7 illustrate such exemplary embodiments.

It would additionally be observed from FIG. 10 that support surface 1004 includes opening 1005, which in a preferred embodiment is in the form of a longitudinal slot. Opening 1005 may be used to affix a resilient support (such as a spring or any other article having shape memory properties and that is configured to compress in response to an applied force, and to revert to its original uncompressed state upon removal of the applied force) to support surface 1004.

FIGS. 6, 7A and 8 illustrate exemplary embodiments of invention, wherein the resilient support Res_(sup), is in the form of a coil spring positioned towards a rear end of the load bearing plate or foot plate. Positioning a resilient support towards a rear end of a foot plate has been found to offer specific advantages for in-line skates—for the reason that it offers a second point of support to the foot plate (i.e. in addition to the pivot point at which the foot plate is coupled with a rocker assembly and serves as the primary point of support), without interfering with pivotability of the foot plate. For example, when pivoting action of the foot plate causes a skater's toe to point towards the skating surface (as illustrated in FIG. 8), the rear surface of the foot plate disengages from resilient support Res_(sup). On the other hand, when the foot plate is positioned parallel to the skating surface, or is in a position where the skater's heel is inclined towards the skating surface, (as illustrated in FIG. 7A), resilient support Res_(sup) provides support to the heel, prevents the heel from being inclined beyond a predefined threshold, and additionally provides shock absorption.

It would be understood that in the embodiment where opening 1005 in support surface 1004 (see FIG. 10) is in the form of a longitudinal slot, the position of resilient support Res_(sup) may be changed relative to the rear end of the foot plate, thereby enabling configuration of the support point with respect to a skater's foot.

The resilient support Res_(sup) may be affixed to rocker arm 1000 at opening 1005 in any one of numerous ways, and using any one or more retaining configurations known in the art.

FIG. 11 illustrates a specific embodiment of the invention wherein resilient support Res_(sup) is a coil spring 1101. Coil spring 1101 may be disposed over core shaft 1102, which core shaft 1102 may comprise a rigid shaft having an outer circumference sized to provide an interference fit with an inner circumference of coil spring 1102—thereby ensuring that once coil spring 1101 is disposed about core shaft 1102, it cannot be displaced without intentionally pulling the two apart. Core shaft 1102 additionally has a hollow interior shaft 1103 which is sized to accommodate retainer bolt 1104. Hollow interior shaft 1103 and retainer bolt 1104 may be complementarily threaded to providing mating engagement therebetween.

Retainer bolt 1104 has a bolt portion 1105 and a head portion 1106, wherein bolt portion 1105 is sized to pass through opening 1005 in support surface 1004 of rocker assembly 1000, and head portion 1106 is sized to resist passage through opening 1005. Bolt portion 1105 accordingly is passed from an underside of support surface 1004 and through opening 1005, until head portion 1106 engages with the underside of support surface 1004. The underside of support surface 1004 thereafter prevents further passage of retainer bolt 1104. Core shaft 1102 is then engaged with retainer bolt 1104 using the complementary threads provided on retainer bolt 1104 and hollow interior shaft 1103. Coil spring 1101 may then be disposed about core shaft 1102, whereafter the interference fit between coil spring 1101 and core shaft 1102 holds coil spring 1101 in place over core shaft 1102. The assembly comprising coil spring 1101, core shaft 1102 and retainer bolt 1104 may be moved to any position along longitudinal opening 1005, by loosening the engagement between retainer bolt 1104 and core shaft 1102, sliding the assembly from the earlier location to the new location within the longitudinal opening, and re-tightening said engagement.

It would be understood that complementary threaded engagement between hollow interior shaft 1103 and retainer bolt 1104 may be achieved by rotating within core shaft 1102 relative to retainer bolt 1104 or vice versa. In an embodiment of the invention, the external surface of core shaft 1102 may have a plurality of holes 1107 disposed thereabout, which holes can accommodate an appropriately sized lever instrument (such as illustrated instrument 1108) to enable core shaft 1102 to be rotated relative to retainer bolt 1104 to loosen or tighten the assembly.

FIG. 12 illustrates a top view of a chassis assembly incorporating rocker assembly 1000 from FIG. 10 along with the assembly for affixing a resilient support as discussed in FIG. 11. As illustrated, chassis assembly 1200 includes rocker 1000 having support surface 1004 and longitudinal opening 1005 therein. A resilient support in the form of coil spring 1101 is affixed within longitudinal opening 1005 and is disposed about core shaft 1102. As would be seen in FIG. 12, the resilient support may be relocated to any position within longitudinal opening, with a view to change the point of support under the foot plate, with which chassis assembly 1200 would eventually engage.

The chassis assembly of an in-line skate may be configured according to any of the methods and apparatus configurations described above to achieve a desired distribution of encountered displacement across each wheel of the chassis assembly. For in-line skates, it has been found to be advantageous for the front wheel to transmit the least amount of the total encountered displacement to the foot plate, with each successive wheel transmitting an increasingly greater amount of the total encountered displacement. It has been found to be particularly advantageous for the rear wheel to transmit the largest part of the total encountered displacement, as this assists a skater in assuming a posture where the skater's centre of gravity is kept forward.

In an embodiment of the invention, an in-line skate comprising a five wheeled, chassis assembly has wheels w₁, w₂, w₃, w₄, and w₅, wherein the chassis assembly is configured to distribute total encountered displacement over wheels w₁ to w₅ in accordance with the below table:

Transmitted percentage of Wheel encountered displacement w₁ 12-18% w₂ 14-20% w₃ 16-23% w₄ 18-25% w₅ 20-27%

In n preferred embodiment of the invention, an in-line skate comprising a five wheeled, chassis assembly has wheels w₁, w₂, w₃, w₄, and w₅, wherein the chassis assembly is configured to distribute total encountered displacement over wheels w₁ to w₅ in accordance with the below table:

Transmitted percentage of Wheel encountered displacement w₁ 16.75% w₂ 19.13% w₃ 20.45% w₄ 21.83% w₅ 21.84%

While the exemplary embodiments of the present invention are described and illustrated herein, it will be appreciated that they are merely illustrative. It will be understood by those skilled in the art that various modifications in form and detail may be made therein without departing from or offending the spirit and scope of the invention as defined by the appended claims. 

I claim:
 1. An in-line wheel chassis assembly comprising: n linearly arranged wheels arranged in a front to rear linear configuration, comprising a front wheel, a rear wheel and at least one intermediate wheel located between the front wheel and the rear wheel; m rocker assemblies, such that m=(n−1), said m rocker assemblies including at least a front rocker assembly and a rear rocker assembly, each including a front end, a rear end, and a pivot point located such that said front end and rear end are pivotable about an axis of rotation passing through said pivot point; wherein, the front rocker assembly is configured such that: the front wheel is rotatably mounted at the front end of said front rocker assembly; and a wheel positioned immediately rearward of the front wheel is rotatably mounted at the rear end of said front rocker assembly; and wherein, the rear rocker assembly is configured such that: the rear wheel is rotatably mounted at the rear end of the rear rocker assembly; the front end of the rear rocker assembly is coupled with a pivot point of a rocker assembly that rotatably mounts a wheel positioned immediately forward of the rear wheel; and the pivot point of the rear rocker assembly is pivotably coupled with a load bearing plate.
 2. The in-line wheel chassis assembly as claimed in claim 1, wherein the m rocker assemblies includes at least one intermediate rocker assembly, and wherein: the intermediate rocker assembly comprises a front end, a rear end, and a pivot point located such that said front end and rear end are pivotable about said pivot point; an intermediate wheel located between the front wheel and the rear wheel is rotatably mounted at the rear end of the intermediate rocker assembly; and the front end of the intermediate rocker assembly is coupled with a pivot point of a rocker assembly that rotatably mounts a wheel positioned immediately forward of the intermediate wheel.
 3. The in-line wheel chassis assembly as claimed in claim 1, the axes of rotation corresponding to each of the n linearly arranged wheels, and the axes of rotation passing through pivot points on each rocker assembly are substantially parallel to each other.
 4. The in-line wheel chassis assembly as claimed in claim 1, wherein the pivotable coupling between the pivot point of the rear rocker assembly and the load bearing plate is the only disengageable interconnection between the m interconnected rocker assemblies and the load bearing plate.
 5. The in-line wheel chassis assembly as claimed in claim 1, wherein: the front rocker assembly comprises an angled rocker arm connecting the front end and rear end of the front rocker assembly; the pivot point of said front rocker assembly is located substantially at a vertex of the angled rocker arm; and the vertex of the angled rocker arm is located further away from the load bearing plate than either of the front and rear ends of the front rocker assembly.
 6. The in-line wheel chassis assembly as claimed in claim 1, wherein radius of the front wheel is greater than radius of the wheel positioned immediately rearward of said front wheel.
 7. An in-line skate comprising: a skate boot; an in-line wheel chassis assembly comprising: n linearly arranged wheels arranged in a front to rear linear configuration, comprising a front wheel, a rear wheel and at least one intermediate wheel located between the front wheel and the rear wheel; m rocker assemblies, such that m=(n−1), said m rocker assemblies including least a front rocker assembly and a rear rocker assembly, each including a front end, a rear end, and a pivot point located such that said front end and rear end are pivotable about an axis of rotation passing through said pivot point; wherein, the front rocker assembly is configured such that: the front wheel is rotatably mounted at the front end of said front rocker assembly; and a wheel positioned immediately rearward of the front wheel is rotatably mounted at the rear end of said front rocker assembly; and wherein, the rear rocker assembly is configured such that: the rear wheel is rotatably mounted at the rear end of the rear rocker assembly; the front end of the rear rocker assembly is coupled with a pivot point of a rocker assembly that rotatably mounts a wheel positioned immediately forward of the rear wheel; and the pivot point of the rear rocker assembly is pivotably coupled with a foot plate affixed to said skate boot.
 8. The in-line skate as claimed in claim 7, wherein the m rocker assemblies comprises at least one intermediate rocker assembly, and wherein: the intermediate rocker assembly comprises a front end, a rear end, and a pivot point located such that said front end and rear end are pivotable about said pivot point; an intermediate wheel located between the front wheel and the rear wheel is rotatably mounted at the rear end of the intermediate rocker assembly; and the front end of the intermediate rocker assembly is coupled with a pivot point of a rocker assembly that rotatably mounts a wheel positioned immediately forward of the intermediate wheel.
 9. The inline skate as claimed in claim 7, wherein a toe portion of the skate boot or of the foot plate is configured to conform to a surface of the front wheel, such that inclining the toe portion towards the front wheel causes said toe portion to interfere with motion of said front wheel thereby reducing motion of the inline skate.
 10. The inline skate as claimed in claim 7, wherein at least one of the m rocker assemblies includes a support surface for supporting the foot plate.
 11. The inline skate as claimed in claim 10, comprising a resilient support affixed to the support surface for resiliently engaging with the foot plate.
 12. The inline skate as claimed in claim 11, wherein the support surface includes a longitudinal opening, and wherein the resilient support may be affixed at a predetermined point within the longitudinal opening, which predetermined point is selected for optimizing support to the skate boot.
 13. The inline skate as claimed in claim 12, wherein the resilient support is affixed at the longitudinal opening by an adjustable retainer, wherein said adjustable retainer enables repositioning of the resilient support at any point within the longitudinal opening.
 14. A method for manufacturing the in-line wheel chassis assembly as claimed in claim 1, the method comprising: determining dimensions for each of the m rocker assemblies and locations for the front end, rear end and pivot point corresponding to each rocker assembly such that, for each of the n wheels, a ratio between displacement encountered at such wheel (D_(enc)) and displacement intended for transmission to the load bearing plate (D_(trans)) satisfies the following expression (I): $\begin{matrix} {{D_{trans} = {D_{{enc}\;}*\frac{\Pi_{k = 1}^{i}l_{k}}{\Pi_{k = 1}^{i}L_{k}}}};} & {{Expression}\mspace{14mu} (I)} \end{matrix}$ and configuring and interconnecting each of the m rocker assemblies and the load bearing plate in accordance with the determined dimensions; wherein: i represents the number of interconnected rocker assemblies used to connect a wheel at which displacement D_(enc) is encountered, with the load bearing surface; l_(k) represents a horizontal distance between (i) a pivot point disposed on the k^(th) rocker assembly and (ii) a wheel axis or pivot point axis disposed on the k^(th) rocker assembly at an end opposite to the end at which the displacement has been transmitted to said k^(th) rocker assembly; and L_(k) represents a horizontal distance between an effective first end and an effective second end of the k^(th) rocker assembly, wherein effective first and second ends: for a front rocker assembly, respectively correspond to points at which said front rocker assembly engages with wheel axes of said front wheel and said adjacent wheel; and for any of the other m rocker assemblies, respectively correspond to a point at which said rocker assembly engages with a pivot point of a separate rocker assembly, and a point at which the rocker assembly engages with a wheel axis. 